|Paleo Slide Set: Tree Rings: Ancient Chronicles of Environmental Change|
|Cutting cross-section from subfossil huon pine (Lagarostrobus franklinii) log, Tasmania.|
| Sometimes it is more useful
to have a full cross section of the tree for analysis, but scientists do
not want to destroy living trees and so take full cross sections only from
dead trees, logs, or stumps. This "remnant" material can remain intact on
the ground or buried for hundreds to thousands of years under certain conditions
(cold and/or dry, under water, or in peat bogs), and can provide very valuable
information about variations in climate beyond the span of living trees.
If these samples overlap in time with living trees, they can be crossdated
and incorporated into a live tree-ring chronology. A European oak chronology
has been developed from subfossil oak buried in peat bogs and river gravel
that spans over 7 millennia (Baillie, 1995). This photo shows a sample being
cut from a subfossil huon pine that died around AD 1200. The sample was
later used to help extend the huon pine chronology back to 200 BC.
Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY: slides
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